Electrical apparatus



Nov. 23, 1948. H. w. ASHTON ELECTRICAL APPARATUS Filed Aug. 8. 1947 PatentedNov. 23, 1948 9 UNITED 's'rA'rl-:s PATENT OFFICE ELECTRICAL APPARATUS Howard W. Ashton, Havertown, Pa., assignor to Oliver W. Storey, Chicago, Ill., as trustee for the partnership of 0. W. Storey Associates, Chicago, Ill.

Application August 8, 1947, Serial No. 787,507

1o claims. (C1. 11i-33o) This invention relates to an electrical appaair or nitrogen or any' other` gas is introduced, ratus and particularly to a capillary electrometer there will be mercury and water in gaseous phase type of transducer. As is well known, a capillary existing under operating conditions. Even in electrometer type of transducer comprises an inthe case of air or any other sas which is introsulating container including a capillary portion, 5 duced, there is undoubtedly some component of said container having at least two substances in mercury and water vapor present. However, the

liquid or liquid-like form to provide at least one pressure of such gas or vapor may be varied over or more interfaces. An example of two subsubstantial limits. Thus, the lower limit will ,be

stances in common use for providing interfaces the vapor pressure of the sulphuric acid solution 4 is mercury and sulphuric acid. Other materials, and mercury at the operating temperature of the such as gallium, may be substituted for mercury; transducer. The upper limit may be determined and a large number of materials, both organic by the strength of the glass. In practice, variaand inorganic, are known for possible substitutions in pressure from the orderI of a fraction of tion for sulphuric acid. While the invention will a millimeter at the lower end up to several atbe described in connection with amercury-sulmospheres are readily possible. phuric acid couple, it will be understood that the 'I'he problem solved by this invention is the invention has general application to capillary maintenance of gas Aor vapor in predetermined electrometer transducers irrespective of the naregions of a capillary electrometer transducer ture of the interface-forming materials. system and the prevention of migration of such In any capillary electrometer type of transgas or vapor from its desired location to an unducer,\there will generally be insulating material desired location in the capillary channel intersuch as glass, a liquid or liquids such as merfaces. While this invention is particularly concury, a gas or vapor. and a solid conducting macerned with a sealed capillary electrometer transterial, such as platinum, for electrical connecducer, it is equally applicable to an open-type tion. It has been found that, in many types of system.

transducer constructions, failure in some in- Inasmuch as such capillary electrometer transstancesl may be due to gas or vapor working along ducers are generally constructed of tubing, such solids and in the liquid to iinally become en as glass for example, and since at least one trained in the interface-forming liquids. In parof the current leads is preferably sealed in at ticular, in a sealed type of capillary electrometer one end, it has been found that special contransducer, such as disclosed and claimed in struction for such lead-in is required at the gas the copending application of William H. Bussey, chamber end of the system. A conventional wire S. N. 573,968, filed January 22, 1945 now Patent lead-in passing through the gas chamber into 2,431,367, issued November 25, 1947, and Howard the mercury-containing chamber generally has W. Ashton, S. N. 740,419, filed April 19, 1947, it is long length, compared to stiffness, so that the a practical impossibility to avoid having some wire may be bent to one side and lie against the gas or vapor in the system. Where the enc1osingglass. It has been found that better contact bemarial is', glass, it is necessary to rely on gas tween wire and mercury is obtained if the wire is or vapor for taking up the displacement of the clear of the glass and dips into the mercury. By liquid columns incident to electrometer opera- 40 virtue of the invention herein, a lead-in contion. y struction is provided, which cooperates with a In some instances, the amount of gas or vapor, constricted channel connecting the gas chamber at one or both ends of the capillary system, may and mercury-containing chamber, to provide a be microscopic.` Nevertheless, such gas Vor vapor desirable and satisfactory lead-in.

doesexist and, by controlling the amount and In order that the invention may be underpressure thereof, substantial control over the stood, it will now be explained in connection with vibration characteristics of the system may be the drawings wherein exemplary embodiments exercised. In some instances, the gas or vapor are shown. Referring to the drawing, Figure 1 may be the same material used in liquid form in shows a capillary electrometer transducer emthe electrometer transducer. 50 bodying the present invention. Figure 2 shows a Thus, it is evident that, in a sealed system diilerent type of capillary electrometer transcontaining mercury and sulphuricl acid diluted ducer including a Bourdon tube also embodying with water, for example, it will not be possible the present invention. Figure 3 illustrates one to have an evacuated region under normal temmanner of making a structure embodying the peratures. Therefore, unless some gas such as present invention.

Referring first to Figure l., a capillary electrometer type of transducer, described and claimed in the copending application of Howard W. Ashton referred to before is shown. In this ligure, glass tube I has capillary channel II therein terminating in enlarged regions orchambers I2 and 13E egionjll is connected by constriction I4 to chamber I5, which may be evacuated or contain gas or vapor. Tube I0 has sealed end I6 in which is disposed wire lead I1. Wire lead I1 passes from the exterior to the interior of the tubular system. Wire lead I1 extends K through chamber I5 and has portion I8 in kinked or coiled form disposed in constriction I4. The lead continues as portion I9 in the form of a straight conductor into region I3. The lead may be of platinum or other conductor inert to mercury and sulphuric acid or whatever liquids are used for forming an interface or for forming a conducting medium between the wire lead and interface-forming liquids.

Disposed within enlarged regions I2 ,and I3 are bodies of mercury. Within capillary channel II are, globules of mercury and other interfaceforming electrolyte,` such as sulphuric acid diluted with water to a concentration of the order of between ten and forty percent. Other interface- A forming liquids may be used as desired.

` Capilla-ry bore II may have a diameter of between about .002" and .015" though dimensions may be used and may have any desired length, such as about .3" although other bore diameters and lengths may be used. Enlarged regions I3 and I5 may have transverse dimensions of about .025," and .050" respectively, and may have a length of about .2". l

Constriction I4 is preferably short and preferably has a substantially larger diameter than capillary channel II. In practice, constriction I4 may have a diameter o frabout twice" that of capillary II, thus giving the constriction about f our rtimes the cross-sectional area. With a capillary' bore of about-'006". a constriction diameterof about .015" has been found satisfactory for use in altran'sducer for phonograph records.

The mercury or other liquid must fill chamber` I3 and preferably extends at least part way into constriction I4. Thus, chamber I3 will be free of gas or vapor. Since the operation of a transducer depends upon displacement of the interfaces and liquid, itwill "be evident that some freedom for movement of the liquid surface must be provided. If the 4cross-sectional area of oonstriction I4 is too` small, the resistance to liquid movementwill be excessive and' will have welldened effects on the over-all vibration response characteristics of the` transducer system.` Howother ever, if the liquidis tobe retained in chamber I3 by capillary force," it is essential that the crosssectionall area of constriction I4 be small enough to provide the desired and necessary capillary forc.

It is, of course, possible to have gas or vapor under pressure within chamber I5 for controlling the vibration-response characteristics of the entire system. In such case, it is essential that the resistance to liquid and gas movement through constriction I4 be small.

By lanalogy to electrical circuits, constriction I4 may be considered as a coupling means having a' certainamount of resistance'. Obviously, if a coupling 'element in an electrical circuit has excessive resistance, the resonance characteristics of the system as a whole may be eliminated,

, the mercury will lbe retained in position by capillary force independently of the kinked portion of the lead. However, where peculiar conditions require, constriction I4 may be made to have substantial length and substantial cross-sectional area. In such case, having the wi-re break the area up into numerous small areas will greatly increase the capillary force existing at the surface of the mercury. The resistance to flow of gas or liquid may, however, be kept quite low if desired.

Capillary bore II and venlarged regions I2 and I3, as well as constriction I4 and chamber I5, are most conveniently -formed in circular cross sec-- tion although other configurations are possible. It is preferred to dimension chamber I3 so that its volume is small as possible consistent with good mechanical construction.

Sealed in the wall of tubel I0 is lead 20 having portion 2| extending within region I2. As shown here, tube I0, adjacent region I2, flares to provide annular portion 25. This portion may have substantial thickness and rigidity. Carried by portion at the edge thereof is diaphragm 21, the diaphragm being joined to-portion 25 at annular flexing region 28. Diaphragm 21 is most conveniently formed of glass, as is tube I0, and is fused to portiony 25. Annular flexing region 28, where the two portions unite, is preferably thin and is endowedv with substantial flexibility. It is preferred to have diaphragm 21 quite rigid, although this may be thin and relatively flexible vif desired.-

'similar to I5 may be provided in communication with regions I2 or 30. Such additional chamber might contain a gas or vapor at a suitable pressure as desired. However, some gas or vapor will be present or may be introduced usually at some part of region 28.

Referring now to bent portion- I8 of the wire lead, Vit will be evident that, if this wire is preformed so that lead portion lI9 extends forwardly of bent portion I8, lead portion I9 will lie within the center of region. I3.

Referring now to Figure 2, a capillary electrometer and Bourdon tube transducer system embodying the present invention is disclosed. The combination of a' capillary electrometer and Bourdon tube is disclosed and claimed in the application of William H. Bussey, referred to before.

`Referring no w to'Figure 2,' capillary electrometer portion I0 has capillary channel II with chambers I 2 and`I3' -at-the two ends. Chamber I2' forms part of a Bourdon tube system with bight portion 32 bent in' agenerally U shape and having a generally oval cross section. Bight portion 32 has end portion 33 connected thereto and terminating in seal 34. Sealed in portion 34 is lead 35 of any suitable wire, such -as platinum, this lead having -eye- 35 formed interface-forming liquids, such as mercury and sulphuric acid, while chamber I2' and the rest of the Bourbon tube system is sealed with a liquid having suitable electrical conductivity, such as mercury for example. Chamber I3 is also lled with a conducting liquid such as mercury. The entire system may be formed of glass in a manner to be explained in connection with the description of Figure 3.

Chamber I3' is connected by constriction Il' to gas chamber I5'. Gas chamber l5' is sealed by a mass of glass I6' and has lead wire I1' passing through seal I5' and through chamber I5'. Lead wire l1' is coiled or kinked at I8' and lhas portion Il' extending into chamber I3. Coiled or kinked portion I8 of the lead wire is so shaped with relation to the transverse dimension of constriction il as to permit portion I8' to bear against the entrance to constriction I4 as shown. Both in Figures l and 2, it is preferred to have the wire so shaped as to break up the space' within or adiacent the constriction into fine capillary spaces whereby large capillary forces are present forv retaining mercury or other liquid in chamber I3'.

Some gas or vapor is present at region 33. In many instances, the amount is so smallthat the bubble cannot be seen with the unaided eye. Its presence may be indicated, however, by evacuating chamber I5 and disposing the entire liquid system as to permit the microscopic gas bubble to expand. No attempt has been made to show the gas at region 33 in proper volumetric proportion.

It will be noted that any gas or vapor at region 33 represents compliance and in combination with the constants of the remainder of the system will control the frequency response characteristic of the system. For use in phonographs, it is preferred to have some gas at 33.

In combination with restricted opening, Il', coiled part I8' of the lead functions to retain liquid in chamber I3' through capillarity. Resistance to vibratory energy transfer is also introduced, and this may be predetermined for the purpose of controlling resonance peaks.

Referring now to Figure 3, blanks for making the capillary electrometer of Figure 2 are shown.

Thus, tubular system 50 is fabricated to provide the same with the capillary chambers and Bourdon tube portion described above in connection with Figure 2. Region 33 of the blank has restricted portion 5I, this portion continuing thereafter as tubular channel 52. Lead 35, having eye 36, has formed thereon glass bead 53. This lead and bead assembly is disposed within the tubular system, it being understood that bead 53 is just small enough to enter into constriction 5I. The bead and constriction are melted together in' a flame.

Lead I1', having performed portion I8' and straight portion I9', has glass bead 55 formed thereon. Glass bead 55 is formed at a suitable portion on lead I1' so that the bead will be spaced at a predetermined distance corresponding to seal l5'. Blank 50 itself Ihas chamber I5 provided with restriction 56. Thus, lead l1 and the bead may be inserted.

Gas chamber l 5 in both structures may be provided with gas or vapor at any desired pressure during the process of manufacture. In addition, the pressure and volume of gas at the other end .of the tubular system, this being in chamber of Figure 1 and in annular region 33 of Figure 2, may also be controlled. By controlling the length and transverse dimension of constriction Il, the

. 6 thickness and character of the glass, it is possible to endow the system with any desired frequency response. Thus, the device as a whole has within it inertia due to liquid, elasticity due to compression of gas or vapor as well as ilexure of glass, and resistance due tothe constricted nature of the sum .of the channels. By proper control of these elements, the entire transducer may be endowed with characteristics which will remain constant over the useful life of the device.

In addition to the above, the disposition of the kinked lead in the manner shown provides for good contact between the wire and mercury under all conditions.

What is claimed is:

1. A capillary electrometer transducer comprising an insulating container having two chambers therein connected by a capillary channel, interface-forming liquidsv in said capillary channel providing at least one interface in said channel,

conducting liquids in said chambers for providing electrical connections to said interface-forming liquids, said container having a third chamber connected to one of saidtwo chambers by a restricted channel with the liquid in said one chamber extending at least partly into said restricted channel, wire leads extending from the exterior of the capillary system to the liquid-filled chambers, one of said wires having a portion `disposed in said third chamber, said one wire extending through said restricted channel into the liquid in said one chamber.

Ying an insulating container having a pair of chambers connected by a capillary channel, said two 'chambers and capillary channel having liquids therein with said capillary channel having at least one interface therein, one of said chambers having a restricted opening at a part remote from said capillary channel, said insulating container having a third chamber aligned with said one chamber and connected thereto through said vrestricted opening, wire leads sealed in said container walls for said liquids, said one chamber having the liquid therein extending into said restricted opening, one wire lead passing through said third chamber and through said restricted opening into said one chamber for making contact with the liquid therein, said wire lead having the portion thereof at said restricted opening shaped so that the wire may lit snugly against said restricted opening, the portion of said wire extending into said one chamber being spaced from the container walls.

5. The structure according to claim 4 wherein said insulating container is sealed, one seal being at said third chamber with the wire passing through ,from the interior of said third chamber to the exterior of the insulating container.

6. The structure according to claim 4 wherein said restricted opening has a transverse dimension of capillary dimensions to prevent migration of gas into said one chamber.

7. The structure according to claim 4 wherein said third chamber is sealed to atmosphere and contains gas at a predetermined pressure and wherein said restricted opening and wire lead cooperate to prevent gas migration into said one chamber.

8. A capillary electrometer comprising an insulating container having three chambers conneoted in series by two capillary channels, liquids in't'wo adjacent chambers and one capillary and forming at least one interface within said capillary for electrometer operation, wire leads sealed in said container and making contact respectively with the liquids in said adjacent chambers, the wire lead for the middle chamber passing through the second capillary and through said third chamber, said middle chamber being filled with liquid and the liquid extending at least partly into said second capillary channel, said second capillary channel having a transverse dimension substantially greater than the diameter of said' last-named wire lead, said last-named wire lead having .the portion passing through said second capillary deformed so that the wire may be sprung iintoand-retained-by the wall of said second capillary, the liquid contacting portion of said wire extending -Irom said second capillary clear of the container lwall. l

9. A capillary electrometer transducer comprising an insulating container having two chambers connected together' by a capillary channel, liquids filling said chambers and channel for forming at least one interface in said channel, one ci said chambers having a restricted opening at a part remote from said capillary channel, said insulating container having a third chamber aligned with said one chamber and connected thereto through said restricted opening, wire leads for said liquids sealed in the container walls, said one chamber having the liquid therein extending into said restricted opening so that said one chamber is completely iilled with liquid, one of said wire leads passing through said restricted opening into said one chamber for making contact with the liquid therein, said third chamber being substantially free of liquid and having gas therein, the other of said pair of chambers containing gas at a. region removed from the capillary channel connecting it with said one chamber, said gas regions, liquids and elasticity of container cooperating to endow the system with predetermined elasticity and mass and thereby determine the frequency response characteristic of the transducer.

10. The structure of claim 9 wherein said wire lead has the' portion thereof at said restricted opening coiled so that the wire may iit snugly against the container wall at said restricted opening, said wire coil and restricted opening providing predetermined resistance for transmission of vibratory energy.

HOWARD W. ASHTON.

No references cited. 

